In this case the pre-form of a wheel with a rotation-symmetrical jacket configuration is placed on a simple rotating tool, a clamping mandrel, which is caused to rotate with the pre-form. On the peripheral edge a plurality of differently shaped stretching rolls engage with radial pressure on the rotation-symmetrical peripheral wall of the pre-form and are moved along this, i.e. in an axial component during the rotation of the pre-form, which on the one hand compresses the material and on the other stretches this material by means of the stretching rolls moving essentially in the axial direction, thereby deforming it to form the rim when a metal wheel is manufactured. On the lower peripheral edge the generally inner rim flange of the wheel to be formed is formed on a recess of the rotary mandrel. This machining process, which is actually a cold forming process, may be carried out an elevated temperature of up to 350° C., but it must be borne in mind here that heating takes place in any case simply because the deformation process takes place by means of the stretching rolls. Such processes are in principle disclosed in US 2003/0145466 A1 or ITVI20040061 A.
One disadvantage is the fact that the inner or lower side of the wheel to be produced is predetermined by the shape of the stretching mandrel and that the peripheral edge of the rim flange can only be end-formed at high cost by lowering the same with the stretching rolls, for which purpose complicated processes are required for controlling the movement on the one hand, and the clamping mandrel may cause interference on the other.